Question

Interpret Biochemical data for microbial identification.

1. Identify function of positive/negative controls.

2. Use positive and negative controls to interpret sample test results (e.g test was positive, negative, or can't be determined).

3. Troubleshoot possible problems with biochemicals experiments.

Answer 1

1. Identify function of positive/negative controls. Use positive and negative controls to interpret sample test results (e.g test was positive, negative, or can't be determined).

Both positive and negative controls are part of good experimental designs. Both positive and negative controls are used to to validate the result of each test.

The negative control is the one where the researcher would expect zero results. The researcher puts up a negative control with the expectation that there would be no outcomes. For example, using distilled water in place of anti microbial agents in checking the zone of inhibition. There would be no zone of inhibition, thus a negative control.

In a positive control there outed be an expectation that the agent would result in a response that is expected by the researcher. If a positive control does not turn out in the manner that has been anticipated by the researcher, then the researcher might have to re do the test. This is more common when the experimental procedure is too complex, Example, using amoxicillin as a antimocrobial agent, resulting in a zone of inhibition.

If both the positive and the negative tests produce the same result, it would mean that there are confounding variables that are interfering with the study and the positive results that are obtained in both the tests are not only because of the treatment.

3. Troubleshoot possible problems with biochemicals experiments.

Possible problems with biochemical experiments:

• When there might be cross reactivity with other chemicals.
• When an analyte is not meant for a particular test.
• When incorrect test conditions would be used.

To resolve these problems, the test has to be properly studied, with measuring its sensitivity and specificity followed by checking all the ingredients that have to be used.